Oh, great. This is turning into an "abortion is right/wrong!" thread!
LOL but I would abort it. Its the best option for the mare (who has a torn vulva & is not approved by the vet to breed), you (who doesn't want a foal), and the foal (who has little chance of a great life unless you keep him).
Just, do the right thing, okay?
Every great dream begins with a dreamer. Always remember, you have within you the strength, the patience, and the passion to reach for the stars to change the world. ~Harriet Tubman